This application is for support of a training program in Allergy and Clinical Immunology, that is designed for post-doctoral medical and pediatric trainees at Yale University School of Medicine. There is a double training faculty. Firstly, clinician-researchers in the Department of Medicine, in the Sections of Allergy, and Clinical Immunology, Rheumatology, Pulmonary, Cardiology, Gastroenterology, Dermatology and Infectious Diseases, and also in Pediatrics. Secondly, a basic sciences immunology training faculty in the Department of Immunobiology. Their expertise spans nearly all of the areas important to allergy, clinical immunology, and modern immunology;including: cellular, molecular, biochemical, antigen-processing/presenting, and signaling research. Some faculty are experts in Lyme disease, which was discovered at Yale in this training program. There is training in Allergy, and Clinical immunology, and some in Rheumatology, Dermatology, Gastroenterology, Pulmonary, and ENT. The training faculty is well equipped with major instruments including: four cytofluorographs, two four-color sorters, oligonucleotide synthesizer, and protein sequinator. This is a small training program, taking only one new fellow per year, with a large faculty emphasizing the need for at least of 3-5 years of laboratory research to prepare trainees for positions in research medicine. The faculty have a strong training record and collaborative research interactions;especially under this Allergy and Clinical Immunology Training Grant. The fellows spend most of their 1st year engaged in clinical activities. The 2nd and 3rd years are spent almost entirely developing a research program under a faculty mentor, while taking various immunobiology courses, participating in weekly seminars and journal clubs, and regularly giving talks on their research, and subjects of interest. In summary, the program offers unique and high quality superb training of outstanding candidates for future positions in academic medicine and pediatrics, and has been quite successful over more than 25 years of continuous funding.